Kids plus germs often equals extreme yuckiness (think stomach flu). But there are some childhood afflictions that -- even though they're not at all dangerous -- are (how to put this?) truly disgusting. First, the good news: The four conditions described here have nothing to do with hygiene and are much more common than you think, so there's no need to be embarrassed. The bad news? Well, read on.

PINWORMSWhat They Are: Tiny white worms that infect the intestines. They're about half an inch long and threadlike in appearance.Yuck Factor: Pretty intense. Pinworm eggs hatch in the small intestine, and the babies move to the large intestine. The adult female worms come out at night to lay their eggs on the outside of the anus. You may even see them (eww!) around your kid's rectum, in his underwear, or in his poop. Fun.How They Spread: Anything touched by anyone with pinworms can spread their eggs. It usually works like this: Kid scratches bottom; eggs embed under the fingernails; kid touches something, leaves eggs behind (they live for two weeks!); eggs get picked up and eventually ingested. Best not to think about the particulars. The main point is, they're very contagious.How You Know He's Got Them: Pinworms itch like crazy at night (that's the female worms laying their eggs). If your kid appears in his pajamas with an itchy rear end night after night (but seems fine in the morning), you may be dealing with the creepy crawlers. You can try to catch a glimpse of the worms, but in the interest of minimizing trauma, throw yourself on your doctor's mercy: Stick a piece of tape on your child's anus, then take it in to the doc's office (he'll examine it under a microscope). If the symptoms all line up, a prescription is in order.What To Do: Your doctor will prescribe a single dose of an anti-parasitic and a second dose two weeks later. It's common to treat the whole family because the worms are so contagious. And get ready for lots of laundry (set the water temp to 130°F). Wash all bedding, stuffed animals, and towels -- and then keep on laundering bedding and towels every few days. Underwear and pj's should be cleaned daily for at least three weeks.

LICEWhat They Are: Parasitic insects that take up residence on the scalp and hair. They attach their eggs to the base of individual hairs, and happily complete their life cycle (nit, nymph, adult) on the human head in one to three weeks.Yuck Factor: High. Visible, bloodsucking insects living in a colony on your kid's head? Just thinking about it is enough to make you scratch your head like crazy. Add in the inherent stigma (these are, after all, the original cooties) associated with a lice infestation, and you're guaranteed a case of the heebie-jeebies.How They Spread: These critters move from head to head, hat to head, pillow to head, comb to head...if it's been on someone's lice-ridden melon, it's a possible vector. Lice can live for a couple of days without human contact, so that baseball cap your kid scored from his new friend at camp could be the source of his buggy hair.How You Know He's Got Them: All you've got to do is look. The adult lice are about the size of a pinhead -- you can see their little heads and legs if you're brave enough to examine closely. The nits are tiny, yellowish ovals that cling to individual hair shafts; they're most common on the hair behind the ears and near the neck. (Nits look a bit like dandruff but stick tight if you try to brush them off.) Lice bites itch, and kids can feel the wee beasties crawling around (wah!) if they've got a really bad case.What To Do: Oh, boy. Most doctors agree that using a pesticide shampoo is most effective (you can nit-pick for appearance's sake). For an alternative route, you can try remedies like olive oil, tea tree oil, or petroleum jelly, which may suffocate the lice; there are also any number of nontoxic products, such as Happyheads. Wash all bedding, clothes, and hairbrushes (at 130°F), vacuum rugs and upholstery, and seal away stuffed animals for two weeks.

RINGWORMWhat They Are: A fungus that forms a red, itchy, raised circle on the skin (despite its name, it's not a worm at all). Fungi enjoy warm, moist areas and often appear in skin folds. (Fun fact: Jock itch is a kind of ringworm!)Yuck Factor: Pretty low, once you get past the name. It sounds worse than it is -- and while it is contagious, at least there are no visible creatures to contend with.How They Spread: Locker rooms, damp towels, wrestling or gymnastic mats, bathing suits or bathing caps, and even goggles can transmit ringworm. And it can spread to different parts of the body through scratching.How You Know He's Got Them: An itchy (very itchy) red rash shaped like a ring is a dead giveaway, though ringworm can simply look red, scaly, and patchy like athlete's foot (a similar fungus) or just a regular old rash. Because it's not always clear, head to the doc; she'll scrape a little skin from the area to examine under a microscope.What To Do: An over-the-counter antifungal cream will usually work. But if the infection is on the scalp or is particularly stubborn (lasting more than two weeks), your doctor will likely order a fungus-killing prescription. You'll want to wash all towels, sheets, bathing suits, and whatnot. One wash does the trick.

SCABIESWhat They Are: Tiny mites that burrow into the skin and cause intense itching, which is usually worse at night. Mites tend to dig in on the hands, feet, and waist.Yuck Factor: Medium to high. Because you can often see the burrows (they look like little curved scratches) and sometimes even the bugs poking out (a tiny black dot), your child's skin, not to mention yours, may actually crawl.How They Spread: These guys make the rounds very easily -- either through contact with an infected person (hugging, holding hands), or through towels, clothes, sheets, and other personal belongings. As with pinworms, if one person has scabies, the whole family's almost surely doomed.How You Know He's Got Them: Your kid starts itching like a maniac. Plus, there are those visible tunnels. Your doctor can probably diagnose by symptoms and examination alone. It can be hard to figure out where your child picked up scabies because symptoms might appear weeks after exposure. Great.What To Do: You'll need a prescription lotion, so get right to the pediatrician if you suspect scabies. The bugs will persist unless the whole family is treated simultaneously. Wash all clothes, bedding, and towels that have been used in the last three days. Your doc can also recommend an antihistamine to help with the itching insanity.